The taskmaster in the story of Cupid and Psyche was Cupid's mother, the love goddess Venus or Aphrodite. Venus had never liked Psyche, so the opportunity of putting her to a series of tests gave Venus a chance to demand the seemingly impossible. In order for Psyche to win back her husband, Cupid, Venus set 4 seemingly impossible tasks before Psyche:

sorting out a huge pile of seeds

retrieving the Golden Fleece,

filling a flask from the water that fills the River Styx, and

returning from the Underworld with a box of the beauty ointment of Proserpina (aka Persephone).

I'm going to have to think on this deeply--I suspect there is some meaning, but then again, it's from a comic novel (The Metamorphosis of Apuleius, aka "The Golden Ass") In the meantime, you can find the full text online here. The Tale of Cupid & Psyche starts at Chapter IV, Section 28. It's quite funny and bawdy, and sheds some light on the freewheeling Roman culture of the time. PS- Welcome to Mythology!
– DukeZhouAug 24 '17 at 19:38

Stage I: Labor of Sorting Seeds - Beginning. Journey of intentionally creating internal order through disciplined action with an aim. We easily imagine the fast movement of the ants working at their aim without distraction and with great speed. It mesmerizes. They can also carry 1000 times their own weight. In life, we are burdened with our own weight and the weight of society. We successfully carry much less than we potentially can once we take the spiritual journey. The vehicle for this labor is mastery of the body, by which I mean a deep conscious knowing and love for the body to be able to use it artfully.Once known, we are able to carry the weight of our own responsibilities, the tensions evoked by engaging the disciplines, as well as the weight that monotony (conscious cycling without sensory stimulation) brings -- this, to gain mastery of the body (ant/instincts).

Stage II: Labor of Acquiring the Golden Fleece - Journey of developing spiritual discernment for light/darkness, good/evil. The vehicle for this labor is the connection with or understanding of the wisdom of nature or natural laws (reed).

Stage III: Labor of Acquiring Holy Water from a Crystal Urn: Journey of making a connection with the soul, the eternal part of ourselves. The vehicle, this time, is heavenly -- Jove's bird or Zeus's bird.

Stage IV: Labor of Making the Journey to the Underworld: The journey of necessary full release from the body with all its' illusions (winning divine loves'favor with beauty believed to come from this elixir) and release from the illusions of the world (many snares laid by Venus). The vehicle is the action of divine love to complete her, emancipate her, humanize her, enlighten her, free her.....

I can't find any sources on a deeper meaning, so I think they were just a way for Venus to keep Psyche away from Cupid. The answer is basically in the source you gave. It says that the tasks are seemingly impossible, and the incentive to make it this way. I'm not sure if this was exactly what you were asking, but that's how I interpreted it.

I agree with one of the earlier statements that the myth is about love, but I also think it can arguably fit a huge variety of complex archetypes. While I'm not a scholar and am not intimately familiar with the myth, I do have a recommendation for a philisophical interpretation of it.

C.S. Lewis' re-telling, 'Til We Have Faces, is an incredibly in-depth look at his view of the myth. He uses the myth to demonstrate the ambivalence of love, and to question the role of the Divine in its application. It is a beautiful and heart wrenching book, if you can get past the traditional dryness of Lewis' writing style.

There are technically two books: the first is a first-person retelling of events by Psyche's sister as sort of an autobiography. The second is about a dream she had, and is where he connects the old myths with his version of events. This is where you have the symbolism of the tasks. His character ruminates over them a bit and provides insight into the symbolism by context of the events of her life in relation to Psyche and the Divine.

I really can't recommend this book enough--it should be considered among the great classics. The audiobook is worth a listen, if you're interested.